Ask the Experts
September 18, 2017 - Updated
November 5, 2007 - Originally Posted

Spray fluxer in wave solder

Spray fluxer in wave solder We have a spray fluxer in a wave solder machine that is cleaned when the spray head is idle. What is the best cleaner to use for this procedure? We are concerned that using the wrong cleaner might corrode the spray nozzle.

A. E.

Expert Panel Responses

It's really very simple, the cleaner should be the same as the solvent in the flux. If the flux you are using is alcohol based then you would use alcohol as the cleaner. If the flux is water based then use water. There is one exception, If the flux is a OA water soluble but alcohol based you would want to use water as the cleaner as well. There is no need to use any of the commercial flux cleaners that are available and it would be expensive to do so.

Greg Hueste
Senior Applications Engineer
Speedline Technologies
Greg joined Electrovert in February 1984. Based out of the Electrovert applications laboratory in Camdenton Missouri, Greg has been in the process applications support role since 2000. His primary responsibilities include providing process and machine applications support for the wave soldering lines as well as process, machine and operations training. He also provides applications support for the reflow and cleaner lines. Greg is a PBET certified trainer and holds two patents on wave solder nozzle design.

The cleaning solvent used to clean the spray head depends upon the flux that you are using. If you are using a "no-clean" flux, isopropyl alcohol (IPA) is the best overall cleaning solvent. All the components of the spray fluxer spray station should be compatible with IPA. If you are using a water-soluble or "water cleanable" flux, water should be used to clean the spray head. However, do not use pure DI water since this may have a deleterious effect on the stainless steel parts in the spray station. If you want to use DI water, mix it first with a small amount of IPA (about 5%), this will prevent it from harming the stainless steel components in your fluxer.

Stuart Erickson
Ultrasonic Systems, Inc.
Mr. Erickson is co-founder of Ultrasonic Systems, Inc. a technology leader in ultrasonic spray technology. Hi is holder of several patents related to ultrasonic spray technology. His roles include product development, technology application, sales and marketing.

I believe most engineers and chemists would agree that IPA (isopropyl alcohol) is considered the best cleaning agent for spray fluxing heads. It is clean and mild and breaks down nearly all flux chemistries. Water is also good with some fluxes, but a few cautionary considerations are worth noting:
  • DI Water (deionized water) may attack metals .
  • Tap water usually contains minerals and contaminants that may clog valves and orifices
If DI water is your preferred cleaning agent, a little trick to take away its aggressive nature is to add a small amount of IPA to the DI water to neutralize it.

Stanley J Soderstrom
Product Engineer
Ultrasonic Systems
Mr. Soderstrom is a veteran of the U.S. Navy where he studied aviation electronics. Stanley has been working in the electronics manufacturing industry for more than 20 years and is considered a top expert in the field of spray fluxing process control.
NOTE: Mr. Soderstron is no longer working at Ultrasonic Systems.

In most wave solder machines, the big worry is the flammability of any solvent you select. So let's make this really easy never, ever use flammable solvents in a wave solder machine. I know many people use IPA as a finger cleaner, down in the back of the machine, but to use flammable solvents near so much heat is a recipe for a tragic accident. In addition, you need a cleaner that is noncorrosive and residue-free. No strong acids or alkaline cleaners can be allowed, plus you wouldn't want those chemicals mixing, even slightly, with your fluxes. In addition, you need a cleaner that is relatively slow-drying, so the solvent has sufficient tack time to work on the flux residues. This eliminates many nonflammable cleaners like HFCs from DuPont and HFE solvents from 3M; great cleaners, but they'll flash-dry so quickly the cleaning won't get properly done. This leaves you with nonflammable, nuetral-pH, water-based hydrocarbon cleaners. My personal suggestion would be to consider one such choice, MicroCare's High-Performance Reflow Oven Cleaner (MCC-ROC), which would work just fine in this application and would use any latent heat from the wave soldering system to deliver enhanced cleaning. Presumably there are similar cleaners from other companies but I don't know a specific part number or blend to recommend.

Mike Jones
Vice President
Micro Care
Mr. Jones is an electronics cleaning and stencil printing specialist. Averaging over one hundred days a year on the road, Mike visits SMT production sites and circuit board repair facilities in every corner of the globe, helping engineers and technicians work through the complex trade-offs today's demanding electronics require.
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